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xen-scsifront.c
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linux-6.19.14/drivers/scsi/xen-scsifront.c
1/* 2 * Xen SCSI frontend driver 3 * 4 * Copyright (c) 2008, FUJITSU Limited 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License version 2 8 * as published by the Free Software Foundation; or, when distributed 9 * separately from the Linux kernel or incorporated into other 10 * software packages, subject to the following license: 11 * 12 * Permission is hereby granted, free of charge, to any person obtaining a copy 13 * of this source file (the "Software"), to deal in the Software without 14 * restriction, including without limitation the rights to use, copy, modify, 15 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 16 * and to permit persons to whom the Software is furnished to do so, subject to 17 * the following conditions: 18 * 19 * The above copyright notice and this permission notice shall be included in 20 * all copies or substantial portions of the Software. 21 * 22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 28 * IN THE SOFTWARE. 29 */ 30 31#include <linux/module.h> 32#include <linux/kernel.h> 33#include <linux/device.h> 34#include <linux/wait.h> 35#include <linux/interrupt.h> 36#include <linux/mutex.h> 37#include <linux/spinlock.h> 38#include <linux/sched.h> 39#include <linux/blkdev.h> 40#include <linux/pfn.h> 41#include <linux/slab.h> 42#include <linux/bitops.h> 43 44#include <scsi/scsi_cmnd.h> 45#include <scsi/scsi_device.h> 46#include <scsi/scsi.h> 47#include <scsi/scsi_host.h> 48 49#include <xen/xen.h> 50#include <xen/xenbus.h> 51#include <xen/grant_table.h> 52#include <xen/events.h> 53#include <xen/page.h> 54 55#include <xen/interface/grant_table.h> 56#include <xen/interface/io/vscsiif.h> 57#include <xen/interface/io/protocols.h> 58 59#include <asm/xen/hypervisor.h> 60 61#define VSCSIFRONT_OP_ADD_LUN 1 62#define VSCSIFRONT_OP_DEL_LUN 2 63#define VSCSIFRONT_OP_READD_LUN 3 64 65/* Tuning point. */ 66#define VSCSIIF_DEFAULT_CMD_PER_LUN 10 67#define VSCSIIF_MAX_TARGET 64 68#define VSCSIIF_MAX_LUN 255 69 70#define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE) 71#define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE 72 73#define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \ 74 sizeof(struct scsiif_request_segment))) 75 76struct vscsifrnt_shadow { 77 /* command between backend and frontend */ 78 unsigned char act; 79 uint8_t nr_segments; 80 uint16_t rqid; 81 uint16_t ref_rqid; 82 83 bool inflight; 84 85 unsigned int nr_grants; /* number of grants in gref[] */ 86 struct scsiif_request_segment *sg; /* scatter/gather elements */ 87 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE]; 88 89 /* Do reset or abort function. */ 90 wait_queue_head_t wq_reset; /* reset work queue */ 91 int wait_reset; /* reset work queue condition */ 92 int32_t rslt_reset; /* reset response status: */ 93 /* SUCCESS or FAILED or: */ 94#define RSLT_RESET_WAITING 0 95#define RSLT_RESET_ERR -1 96 97 /* Requested struct scsi_cmnd is stored from kernel. */ 98 struct scsi_cmnd *sc; 99 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL]; 100}; 101 102struct vscsifrnt_info { 103 struct xenbus_device *dev; 104 105 struct Scsi_Host *host; 106 enum { 107 STATE_INACTIVE, 108 STATE_ACTIVE, 109 STATE_ERROR 110 } host_active; 111 112 unsigned int evtchn; 113 unsigned int irq; 114 115 grant_ref_t ring_ref; 116 struct vscsiif_front_ring ring; 117 struct vscsiif_response ring_rsp; 118 119 spinlock_t shadow_lock; 120 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS); 121 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS]; 122 123 /* Following items are protected by the host lock. */ 124 wait_queue_head_t wq_sync; 125 wait_queue_head_t wq_pause; 126 unsigned int wait_ring_available:1; 127 unsigned int waiting_pause:1; 128 unsigned int pause:1; 129 unsigned callers; 130 131 char dev_state_path[64]; 132 struct task_struct *curr; 133}; 134 135static DEFINE_MUTEX(scsifront_mutex); 136 137static void scsifront_wake_up(struct vscsifrnt_info *info) 138{ 139 info->wait_ring_available = 0; 140 wake_up(&info->wq_sync); 141} 142 143static int scsifront_get_rqid(struct vscsifrnt_info *info) 144{ 145 unsigned long flags; 146 int free; 147 148 spin_lock_irqsave(&info->shadow_lock, flags); 149 150 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 151 __clear_bit(free, info->shadow_free_bitmap); 152 153 spin_unlock_irqrestore(&info->shadow_lock, flags); 154 155 return free; 156} 157 158static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) 159{ 160 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 161 162 __set_bit(id, info->shadow_free_bitmap); 163 info->shadow[id] = NULL; 164 165 return empty || info->wait_ring_available; 166} 167 168static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) 169{ 170 unsigned long flags; 171 int kick; 172 173 spin_lock_irqsave(&info->shadow_lock, flags); 174 kick = _scsifront_put_rqid(info, id); 175 spin_unlock_irqrestore(&info->shadow_lock, flags); 176 177 if (kick) 178 scsifront_wake_up(info); 179} 180 181static int scsifront_do_request(struct vscsifrnt_info *info, 182 struct vscsifrnt_shadow *shadow) 183{ 184 struct vscsiif_front_ring *ring = &(info->ring); 185 struct vscsiif_request *ring_req; 186 struct scsi_cmnd *sc = shadow->sc; 187 uint32_t id; 188 int i, notify; 189 190 if (RING_FULL(&info->ring)) 191 return -EBUSY; 192 193 id = scsifront_get_rqid(info); /* use id in response */ 194 if (id >= VSCSIIF_MAX_REQS) 195 return -EBUSY; 196 197 info->shadow[id] = shadow; 198 shadow->rqid = id; 199 200 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt); 201 ring->req_prod_pvt++; 202 203 ring_req->rqid = id; 204 ring_req->act = shadow->act; 205 ring_req->ref_rqid = shadow->ref_rqid; 206 ring_req->nr_segments = shadow->nr_segments; 207 208 ring_req->id = sc->device->id; 209 ring_req->lun = sc->device->lun; 210 ring_req->channel = sc->device->channel; 211 ring_req->cmd_len = sc->cmd_len; 212 213 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE); 214 215 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len); 216 217 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction; 218 ring_req->timeout_per_command = scsi_cmd_to_rq(sc)->timeout / HZ; 219 220 for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++) 221 ring_req->seg[i] = shadow->seg[i]; 222 223 shadow->inflight = true; 224 225 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify); 226 if (notify) 227 notify_remote_via_irq(info->irq); 228 229 return 0; 230} 231 232static void scsifront_set_error(struct vscsifrnt_info *info, const char *msg) 233{ 234 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME "%s\n" 235 "Disabling device for further use\n", msg); 236 info->host_active = STATE_ERROR; 237} 238 239static void scsifront_gnttab_done(struct vscsifrnt_info *info, 240 struct vscsifrnt_shadow *shadow) 241{ 242 int i; 243 244 if (shadow->sc->sc_data_direction == DMA_NONE) 245 return; 246 247 for (i = 0; i < shadow->nr_grants; i++) { 248 if (unlikely(!gnttab_try_end_foreign_access(shadow->gref[i]))) { 249 scsifront_set_error(info, "grant still in use by backend"); 250 return; 251 } 252 } 253 254 kfree(shadow->sg); 255} 256 257static unsigned int scsifront_host_byte(int32_t rslt) 258{ 259 switch (XEN_VSCSIIF_RSLT_HOST(rslt)) { 260 case XEN_VSCSIIF_RSLT_HOST_OK: 261 return DID_OK; 262 case XEN_VSCSIIF_RSLT_HOST_NO_CONNECT: 263 return DID_NO_CONNECT; 264 case XEN_VSCSIIF_RSLT_HOST_BUS_BUSY: 265 return DID_BUS_BUSY; 266 case XEN_VSCSIIF_RSLT_HOST_TIME_OUT: 267 return DID_TIME_OUT; 268 case XEN_VSCSIIF_RSLT_HOST_BAD_TARGET: 269 return DID_BAD_TARGET; 270 case XEN_VSCSIIF_RSLT_HOST_ABORT: 271 return DID_ABORT; 272 case XEN_VSCSIIF_RSLT_HOST_PARITY: 273 return DID_PARITY; 274 case XEN_VSCSIIF_RSLT_HOST_ERROR: 275 return DID_ERROR; 276 case XEN_VSCSIIF_RSLT_HOST_RESET: 277 return DID_RESET; 278 case XEN_VSCSIIF_RSLT_HOST_BAD_INTR: 279 return DID_BAD_INTR; 280 case XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH: 281 return DID_PASSTHROUGH; 282 case XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR: 283 return DID_SOFT_ERROR; 284 case XEN_VSCSIIF_RSLT_HOST_IMM_RETRY: 285 return DID_IMM_RETRY; 286 case XEN_VSCSIIF_RSLT_HOST_REQUEUE: 287 return DID_REQUEUE; 288 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED: 289 return DID_TRANSPORT_DISRUPTED; 290 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST: 291 return DID_TRANSPORT_FAILFAST; 292 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL: 293 return DID_TRANSPORT_MARGINAL; 294 default: 295 return DID_ERROR; 296 } 297} 298 299static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info, 300 struct vscsiif_response *ring_rsp) 301{ 302 struct vscsifrnt_shadow *shadow; 303 struct scsi_cmnd *sc; 304 uint32_t id; 305 uint8_t sense_len; 306 307 id = ring_rsp->rqid; 308 shadow = info->shadow[id]; 309 sc = shadow->sc; 310 311 BUG_ON(sc == NULL); 312 313 scsifront_gnttab_done(info, shadow); 314 if (info->host_active == STATE_ERROR) 315 return; 316 scsifront_put_rqid(info, id); 317 318 set_host_byte(sc, scsifront_host_byte(ring_rsp->rslt)); 319 set_status_byte(sc, XEN_VSCSIIF_RSLT_STATUS(ring_rsp->rslt)); 320 scsi_set_resid(sc, ring_rsp->residual_len); 321 322 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE, 323 ring_rsp->sense_len); 324 325 if (sense_len) 326 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len); 327 328 scsi_done(sc); 329} 330 331static void scsifront_sync_cmd_done(struct vscsifrnt_info *info, 332 struct vscsiif_response *ring_rsp) 333{ 334 uint16_t id = ring_rsp->rqid; 335 unsigned long flags; 336 struct vscsifrnt_shadow *shadow = info->shadow[id]; 337 int kick; 338 339 spin_lock_irqsave(&info->shadow_lock, flags); 340 shadow->wait_reset = 1; 341 switch (shadow->rslt_reset) { 342 case RSLT_RESET_WAITING: 343 if (ring_rsp->rslt == XEN_VSCSIIF_RSLT_RESET_SUCCESS) 344 shadow->rslt_reset = SUCCESS; 345 else 346 shadow->rslt_reset = FAILED; 347 break; 348 case RSLT_RESET_ERR: 349 kick = _scsifront_put_rqid(info, id); 350 spin_unlock_irqrestore(&info->shadow_lock, flags); 351 kfree(shadow); 352 if (kick) 353 scsifront_wake_up(info); 354 return; 355 default: 356 scsifront_set_error(info, "bad reset state"); 357 break; 358 } 359 spin_unlock_irqrestore(&info->shadow_lock, flags); 360 361 wake_up(&shadow->wq_reset); 362} 363 364static void scsifront_do_response(struct vscsifrnt_info *info, 365 struct vscsiif_response *ring_rsp) 366{ 367 struct vscsifrnt_shadow *shadow; 368 369 if (ring_rsp->rqid >= VSCSIIF_MAX_REQS || 370 !info->shadow[ring_rsp->rqid]->inflight) { 371 scsifront_set_error(info, "illegal rqid returned by backend!"); 372 return; 373 } 374 shadow = info->shadow[ring_rsp->rqid]; 375 shadow->inflight = false; 376 377 if (shadow->act == VSCSIIF_ACT_SCSI_CDB) 378 scsifront_cdb_cmd_done(info, ring_rsp); 379 else 380 scsifront_sync_cmd_done(info, ring_rsp); 381} 382 383static int scsifront_ring_drain(struct vscsifrnt_info *info, 384 unsigned int *eoiflag) 385{ 386 struct vscsiif_response ring_rsp; 387 RING_IDX i, rp; 388 int more_to_do = 0; 389 390 rp = READ_ONCE(info->ring.sring->rsp_prod); 391 virt_rmb(); /* ordering required respective to backend */ 392 if (RING_RESPONSE_PROD_OVERFLOW(&info->ring, rp)) { 393 scsifront_set_error(info, "illegal number of responses"); 394 return 0; 395 } 396 for (i = info->ring.rsp_cons; i != rp; i++) { 397 RING_COPY_RESPONSE(&info->ring, i, &ring_rsp); 398 scsifront_do_response(info, &ring_rsp); 399 if (info->host_active == STATE_ERROR) 400 return 0; 401 *eoiflag &= ~XEN_EOI_FLAG_SPURIOUS; 402 } 403 404 info->ring.rsp_cons = i; 405 406 if (i != info->ring.req_prod_pvt) 407 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 408 else 409 info->ring.sring->rsp_event = i + 1; 410 411 return more_to_do; 412} 413 414static int scsifront_cmd_done(struct vscsifrnt_info *info, 415 unsigned int *eoiflag) 416{ 417 int more_to_do; 418 unsigned long flags; 419 420 spin_lock_irqsave(info->host->host_lock, flags); 421 422 more_to_do = scsifront_ring_drain(info, eoiflag); 423 424 info->wait_ring_available = 0; 425 426 spin_unlock_irqrestore(info->host->host_lock, flags); 427 428 wake_up(&info->wq_sync); 429 430 return more_to_do; 431} 432 433static irqreturn_t scsifront_irq_fn(int irq, void *dev_id) 434{ 435 struct vscsifrnt_info *info = dev_id; 436 unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS; 437 438 if (info->host_active == STATE_ERROR) { 439 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS); 440 return IRQ_HANDLED; 441 } 442 443 while (scsifront_cmd_done(info, &eoiflag)) 444 /* Yield point for this unbounded loop. */ 445 cond_resched(); 446 447 xen_irq_lateeoi(irq, eoiflag); 448 449 return IRQ_HANDLED; 450} 451 452static void scsifront_finish_all(struct vscsifrnt_info *info) 453{ 454 unsigned int i, dummy; 455 struct vscsiif_response resp; 456 457 scsifront_ring_drain(info, &dummy); 458 459 for (i = 0; i < VSCSIIF_MAX_REQS; i++) { 460 if (test_bit(i, info->shadow_free_bitmap)) 461 continue; 462 resp.rqid = i; 463 resp.sense_len = 0; 464 resp.rslt = DID_RESET << 16; 465 resp.residual_len = 0; 466 scsifront_do_response(info, &resp); 467 } 468} 469 470static int map_data_for_request(struct vscsifrnt_info *info, 471 struct scsi_cmnd *sc, 472 struct vscsifrnt_shadow *shadow) 473{ 474 grant_ref_t gref_head; 475 struct page *page; 476 int err, ref, ref_cnt = 0; 477 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE); 478 unsigned int i, off, len, bytes; 479 unsigned int data_len = scsi_bufflen(sc); 480 unsigned int data_grants = 0, seg_grants = 0; 481 struct scatterlist *sg; 482 struct scsiif_request_segment *seg; 483 484 if (sc->sc_data_direction == DMA_NONE || !data_len) 485 return 0; 486 487 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) 488 data_grants += PFN_UP(sg->offset + sg->length); 489 490 if (data_grants > VSCSIIF_SG_TABLESIZE) { 491 if (data_grants > info->host->sg_tablesize) { 492 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 493 "Unable to map request_buffer for command!\n"); 494 return -E2BIG; 495 } 496 seg_grants = vscsiif_grants_sg(data_grants); 497 shadow->sg = kcalloc(data_grants, 498 sizeof(struct scsiif_request_segment), GFP_ATOMIC); 499 if (!shadow->sg) 500 return -ENOMEM; 501 } 502 seg = shadow->sg ? : shadow->seg; 503 504 err = gnttab_alloc_grant_references(seg_grants + data_grants, 505 &gref_head); 506 if (err) { 507 kfree(shadow->sg); 508 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME 509 "gnttab_alloc_grant_references() error\n"); 510 return -ENOMEM; 511 } 512 513 if (seg_grants) { 514 page = virt_to_page(seg); 515 off = offset_in_page(seg); 516 len = sizeof(struct scsiif_request_segment) * data_grants; 517 while (len > 0) { 518 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 519 520 ref = gnttab_claim_grant_reference(&gref_head); 521 BUG_ON(ref == -ENOSPC); 522 523 gnttab_grant_foreign_access_ref(ref, 524 info->dev->otherend_id, 525 xen_page_to_gfn(page), 1); 526 shadow->gref[ref_cnt] = ref; 527 shadow->seg[ref_cnt].gref = ref; 528 shadow->seg[ref_cnt].offset = (uint16_t)off; 529 shadow->seg[ref_cnt].length = (uint16_t)bytes; 530 531 page++; 532 len -= bytes; 533 off = 0; 534 ref_cnt++; 535 } 536 BUG_ON(seg_grants < ref_cnt); 537 seg_grants = ref_cnt; 538 } 539 540 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) { 541 page = sg_page(sg); 542 off = sg->offset; 543 len = sg->length; 544 545 while (len > 0 && data_len > 0) { 546 /* 547 * sg sends a scatterlist that is larger than 548 * the data_len it wants transferred for certain 549 * IO sizes. 550 */ 551 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 552 bytes = min(bytes, data_len); 553 554 ref = gnttab_claim_grant_reference(&gref_head); 555 BUG_ON(ref == -ENOSPC); 556 557 gnttab_grant_foreign_access_ref(ref, 558 info->dev->otherend_id, 559 xen_page_to_gfn(page), 560 grant_ro); 561 562 shadow->gref[ref_cnt] = ref; 563 seg->gref = ref; 564 seg->offset = (uint16_t)off; 565 seg->length = (uint16_t)bytes; 566 567 page++; 568 seg++; 569 len -= bytes; 570 data_len -= bytes; 571 off = 0; 572 ref_cnt++; 573 } 574 } 575 576 if (seg_grants) 577 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants; 578 else 579 shadow->nr_segments = (uint8_t)ref_cnt; 580 shadow->nr_grants = ref_cnt; 581 582 return 0; 583} 584 585static int scsifront_enter(struct vscsifrnt_info *info) 586{ 587 if (info->pause) 588 return 1; 589 info->callers++; 590 return 0; 591} 592 593static void scsifront_return(struct vscsifrnt_info *info) 594{ 595 info->callers--; 596 if (info->callers) 597 return; 598 599 if (!info->waiting_pause) 600 return; 601 602 info->waiting_pause = 0; 603 wake_up(&info->wq_pause); 604} 605 606static int scsifront_queuecommand(struct Scsi_Host *shost, 607 struct scsi_cmnd *sc) 608{ 609 struct vscsifrnt_info *info = shost_priv(shost); 610 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc); 611 unsigned long flags; 612 int err; 613 614 if (info->host_active == STATE_ERROR) 615 return SCSI_MLQUEUE_HOST_BUSY; 616 617 sc->result = 0; 618 619 shadow->sc = sc; 620 shadow->act = VSCSIIF_ACT_SCSI_CDB; 621 622 spin_lock_irqsave(shost->host_lock, flags); 623 if (scsifront_enter(info)) { 624 spin_unlock_irqrestore(shost->host_lock, flags); 625 return SCSI_MLQUEUE_HOST_BUSY; 626 } 627 628 err = map_data_for_request(info, sc, shadow); 629 if (err < 0) { 630 pr_debug("%s: err %d\n", __func__, err); 631 scsifront_return(info); 632 spin_unlock_irqrestore(shost->host_lock, flags); 633 if (err == -ENOMEM) 634 return SCSI_MLQUEUE_HOST_BUSY; 635 sc->result = DID_ERROR << 16; 636 scsi_done(sc); 637 return 0; 638 } 639 640 if (scsifront_do_request(info, shadow)) { 641 scsifront_gnttab_done(info, shadow); 642 goto busy; 643 } 644 645 scsifront_return(info); 646 spin_unlock_irqrestore(shost->host_lock, flags); 647 648 return 0; 649 650busy: 651 scsifront_return(info); 652 spin_unlock_irqrestore(shost->host_lock, flags); 653 pr_debug("%s: busy\n", __func__); 654 return SCSI_MLQUEUE_HOST_BUSY; 655} 656 657/* 658 * Any exception handling (reset or abort) must be forwarded to the backend. 659 * We have to wait until an answer is returned. This answer contains the 660 * result to be returned to the requestor. 661 */ 662static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act) 663{ 664 struct Scsi_Host *host = sc->device->host; 665 struct vscsifrnt_info *info = shost_priv(host); 666 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc); 667 int err = 0; 668 669 if (info->host_active == STATE_ERROR) 670 return FAILED; 671 672 shadow = kzalloc(sizeof(*shadow), GFP_NOIO); 673 if (!shadow) 674 return FAILED; 675 676 shadow->act = act; 677 shadow->rslt_reset = RSLT_RESET_WAITING; 678 shadow->sc = sc; 679 shadow->ref_rqid = s->rqid; 680 init_waitqueue_head(&shadow->wq_reset); 681 682 spin_lock_irq(host->host_lock); 683 684 for (;;) { 685 if (scsifront_enter(info)) 686 goto fail; 687 688 if (!scsifront_do_request(info, shadow)) 689 break; 690 691 scsifront_return(info); 692 if (err) 693 goto fail; 694 info->wait_ring_available = 1; 695 spin_unlock_irq(host->host_lock); 696 err = wait_event_interruptible(info->wq_sync, 697 !info->wait_ring_available); 698 spin_lock_irq(host->host_lock); 699 } 700 701 spin_unlock_irq(host->host_lock); 702 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset); 703 spin_lock_irq(host->host_lock); 704 705 if (!err) { 706 err = shadow->rslt_reset; 707 scsifront_put_rqid(info, shadow->rqid); 708 kfree(shadow); 709 } else { 710 spin_lock(&info->shadow_lock); 711 shadow->rslt_reset = RSLT_RESET_ERR; 712 spin_unlock(&info->shadow_lock); 713 err = FAILED; 714 } 715 716 scsifront_return(info); 717 spin_unlock_irq(host->host_lock); 718 return err; 719 720fail: 721 spin_unlock_irq(host->host_lock); 722 kfree(shadow); 723 return FAILED; 724} 725 726static int scsifront_eh_abort_handler(struct scsi_cmnd *sc) 727{ 728 pr_debug("%s\n", __func__); 729 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT); 730} 731 732static int scsifront_dev_reset_handler(struct scsi_cmnd *sc) 733{ 734 pr_debug("%s\n", __func__); 735 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET); 736} 737 738static int scsifront_sdev_configure(struct scsi_device *sdev, 739 struct queue_limits *lim) 740{ 741 struct vscsifrnt_info *info = shost_priv(sdev->host); 742 int err; 743 744 if (info->host_active == STATE_ERROR) 745 return -EIO; 746 747 if (current == info->curr) { 748 err = xenbus_printf(XBT_NIL, info->dev->nodename, 749 info->dev_state_path, "%d", XenbusStateConnected); 750 if (err) { 751 xenbus_dev_error(info->dev, err, 752 "%s: writing dev_state_path", __func__); 753 return err; 754 } 755 } 756 757 return 0; 758} 759 760static void scsifront_sdev_destroy(struct scsi_device *sdev) 761{ 762 struct vscsifrnt_info *info = shost_priv(sdev->host); 763 int err; 764 765 if (current == info->curr) { 766 err = xenbus_printf(XBT_NIL, info->dev->nodename, 767 info->dev_state_path, "%d", XenbusStateClosed); 768 if (err) 769 xenbus_dev_error(info->dev, err, 770 "%s: writing dev_state_path", __func__); 771 } 772} 773 774static const struct scsi_host_template scsifront_sht = { 775 .module = THIS_MODULE, 776 .name = "Xen SCSI frontend driver", 777 .queuecommand = scsifront_queuecommand, 778 .eh_abort_handler = scsifront_eh_abort_handler, 779 .eh_device_reset_handler = scsifront_dev_reset_handler, 780 .sdev_configure = scsifront_sdev_configure, 781 .sdev_destroy = scsifront_sdev_destroy, 782 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN, 783 .can_queue = VSCSIIF_MAX_REQS, 784 .this_id = -1, 785 .cmd_size = sizeof(struct vscsifrnt_shadow), 786 .sg_tablesize = VSCSIIF_SG_TABLESIZE, 787 .proc_name = "scsifront", 788}; 789 790static int scsifront_alloc_ring(struct vscsifrnt_info *info) 791{ 792 struct xenbus_device *dev = info->dev; 793 struct vscsiif_sring *sring; 794 int err; 795 796 /***** Frontend to Backend ring start *****/ 797 err = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&sring, 1, 798 &info->ring_ref); 799 if (err) 800 return err; 801 802 XEN_FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 803 804 err = xenbus_alloc_evtchn(dev, &info->evtchn); 805 if (err) { 806 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn"); 807 goto free_gnttab; 808 } 809 810 err = bind_evtchn_to_irq_lateeoi(info->evtchn); 811 if (err <= 0) { 812 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq"); 813 goto free_gnttab; 814 } 815 816 info->irq = err; 817 818 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn, 819 IRQF_ONESHOT, "scsifront", info); 820 if (err) { 821 xenbus_dev_fatal(dev, err, "request_threaded_irq"); 822 goto free_irq; 823 } 824 825 return 0; 826 827/* free resource */ 828free_irq: 829 unbind_from_irqhandler(info->irq, info); 830free_gnttab: 831 xenbus_teardown_ring((void **)&sring, 1, &info->ring_ref); 832 833 return err; 834} 835 836static void scsifront_free_ring(struct vscsifrnt_info *info) 837{ 838 unbind_from_irqhandler(info->irq, info); 839 xenbus_teardown_ring((void **)&info->ring.sring, 1, &info->ring_ref); 840} 841 842static int scsifront_init_ring(struct vscsifrnt_info *info) 843{ 844 struct xenbus_device *dev = info->dev; 845 struct xenbus_transaction xbt; 846 int err; 847 848 pr_debug("%s\n", __func__); 849 850 err = scsifront_alloc_ring(info); 851 if (err) 852 return err; 853 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn); 854 855again: 856 err = xenbus_transaction_start(&xbt); 857 if (err) 858 xenbus_dev_fatal(dev, err, "starting transaction"); 859 860 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u", 861 info->ring_ref); 862 if (err) { 863 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref"); 864 goto fail; 865 } 866 867 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u", 868 info->evtchn); 869 870 if (err) { 871 xenbus_dev_fatal(dev, err, "%s", "writing event-channel"); 872 goto fail; 873 } 874 875 err = xenbus_transaction_end(xbt, 0); 876 if (err) { 877 if (err == -EAGAIN) 878 goto again; 879 xenbus_dev_fatal(dev, err, "completing transaction"); 880 goto free_sring; 881 } 882 883 return 0; 884 885fail: 886 xenbus_transaction_end(xbt, 1); 887free_sring: 888 scsifront_free_ring(info); 889 890 return err; 891} 892 893 894static int scsifront_probe(struct xenbus_device *dev, 895 const struct xenbus_device_id *id) 896{ 897 struct vscsifrnt_info *info; 898 struct Scsi_Host *host; 899 int err = -ENOMEM; 900 char name[TASK_COMM_LEN]; 901 902 host = scsi_host_alloc(&scsifront_sht, sizeof(*info)); 903 if (!host) { 904 xenbus_dev_fatal(dev, err, "fail to allocate scsi host"); 905 return err; 906 } 907 info = shost_priv(host); 908 909 dev_set_drvdata(&dev->dev, info); 910 info->dev = dev; 911 912 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); 913 914 err = scsifront_init_ring(info); 915 if (err) { 916 scsi_host_put(host); 917 return err; 918 } 919 920 init_waitqueue_head(&info->wq_sync); 921 init_waitqueue_head(&info->wq_pause); 922 spin_lock_init(&info->shadow_lock); 923 924 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no); 925 926 host->max_id = VSCSIIF_MAX_TARGET; 927 host->max_channel = 0; 928 host->max_lun = VSCSIIF_MAX_LUN; 929 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512; 930 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE; 931 932 err = scsi_add_host(host, &dev->dev); 933 if (err) { 934 dev_err(&dev->dev, "fail to add scsi host %d\n", err); 935 goto free_sring; 936 } 937 info->host = host; 938 info->host_active = STATE_ACTIVE; 939 940 xenbus_switch_state(dev, XenbusStateInitialised); 941 942 return 0; 943 944free_sring: 945 scsifront_free_ring(info); 946 scsi_host_put(host); 947 return err; 948} 949 950static int scsifront_resume(struct xenbus_device *dev) 951{ 952 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 953 struct Scsi_Host *host = info->host; 954 int err; 955 956 spin_lock_irq(host->host_lock); 957 958 /* Finish all still pending commands. */ 959 scsifront_finish_all(info); 960 961 spin_unlock_irq(host->host_lock); 962 963 /* Reconnect to dom0. */ 964 scsifront_free_ring(info); 965 err = scsifront_init_ring(info); 966 if (err) { 967 dev_err(&dev->dev, "fail to resume %d\n", err); 968 scsi_host_put(host); 969 return err; 970 } 971 972 xenbus_switch_state(dev, XenbusStateInitialised); 973 974 return 0; 975} 976 977static int scsifront_suspend(struct xenbus_device *dev) 978{ 979 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 980 struct Scsi_Host *host = info->host; 981 int err = 0; 982 983 /* No new commands for the backend. */ 984 spin_lock_irq(host->host_lock); 985 info->pause = 1; 986 while (info->callers && !err) { 987 info->waiting_pause = 1; 988 info->wait_ring_available = 0; 989 spin_unlock_irq(host->host_lock); 990 wake_up(&info->wq_sync); 991 err = wait_event_interruptible(info->wq_pause, 992 !info->waiting_pause); 993 spin_lock_irq(host->host_lock); 994 } 995 spin_unlock_irq(host->host_lock); 996 return err; 997} 998 999static void scsifront_remove(struct xenbus_device *dev) 1000{ 1001 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 1002 1003 pr_debug("%s: %s removed\n", __func__, dev->nodename); 1004 1005 mutex_lock(&scsifront_mutex); 1006 if (info->host_active != STATE_INACTIVE) { 1007 /* Scsi_host not yet removed */ 1008 scsi_remove_host(info->host); 1009 info->host_active = STATE_INACTIVE; 1010 } 1011 mutex_unlock(&scsifront_mutex); 1012 1013 scsifront_free_ring(info); 1014 scsi_host_put(info->host); 1015} 1016 1017static void scsifront_disconnect(struct vscsifrnt_info *info) 1018{ 1019 struct xenbus_device *dev = info->dev; 1020 struct Scsi_Host *host = info->host; 1021 1022 pr_debug("%s: %s disconnect\n", __func__, dev->nodename); 1023 1024 /* 1025 * When this function is executed, all devices of 1026 * Frontend have been deleted. 1027 * Therefore, it need not block I/O before remove_host. 1028 */ 1029 1030 mutex_lock(&scsifront_mutex); 1031 if (info->host_active != STATE_INACTIVE) { 1032 scsi_remove_host(host); 1033 info->host_active = STATE_INACTIVE; 1034 } 1035 mutex_unlock(&scsifront_mutex); 1036 1037 xenbus_frontend_closed(dev); 1038} 1039 1040static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op) 1041{ 1042 struct xenbus_device *dev = info->dev; 1043 int i, err = 0; 1044 char str[64]; 1045 char **dir; 1046 unsigned int dir_n = 0; 1047 unsigned int device_state; 1048 unsigned int hst, chn, tgt, lun; 1049 struct scsi_device *sdev; 1050 1051 if (info->host_active == STATE_ERROR) 1052 return; 1053 1054 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n); 1055 if (IS_ERR(dir)) 1056 return; 1057 1058 /* mark current task as the one allowed to modify device states */ 1059 BUG_ON(info->curr); 1060 info->curr = current; 1061 1062 for (i = 0; i < dir_n; i++) { 1063 /* read status */ 1064 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]); 1065 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u", 1066 &device_state); 1067 if (XENBUS_EXIST_ERR(err)) 1068 continue; 1069 1070 /* virtual SCSI device */ 1071 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]); 1072 err = xenbus_scanf(XBT_NIL, dev->otherend, str, 1073 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun); 1074 if (XENBUS_EXIST_ERR(err)) 1075 continue; 1076 1077 /* 1078 * Front device state path, used in sdev_configure called 1079 * on successfull scsi_add_device, and in sdev_destroy called 1080 * on remove of a device. 1081 */ 1082 snprintf(info->dev_state_path, sizeof(info->dev_state_path), 1083 "vscsi-devs/%s/state", dir[i]); 1084 1085 switch (op) { 1086 case VSCSIFRONT_OP_ADD_LUN: 1087 if (device_state != XenbusStateInitialised) 1088 break; 1089 1090 if (scsi_add_device(info->host, chn, tgt, lun)) { 1091 dev_err(&dev->dev, "scsi_add_device\n"); 1092 err = xenbus_printf(XBT_NIL, dev->nodename, 1093 info->dev_state_path, 1094 "%d", XenbusStateClosed); 1095 if (err) 1096 xenbus_dev_error(dev, err, 1097 "%s: writing dev_state_path", __func__); 1098 } 1099 break; 1100 case VSCSIFRONT_OP_DEL_LUN: 1101 if (device_state != XenbusStateClosing) 1102 break; 1103 1104 sdev = scsi_device_lookup(info->host, chn, tgt, lun); 1105 if (sdev) { 1106 scsi_remove_device(sdev); 1107 scsi_device_put(sdev); 1108 } 1109 break; 1110 case VSCSIFRONT_OP_READD_LUN: 1111 if (device_state == XenbusStateConnected) { 1112 err = xenbus_printf(XBT_NIL, dev->nodename, 1113 info->dev_state_path, 1114 "%d", XenbusStateConnected); 1115 if (err) 1116 xenbus_dev_error(dev, err, 1117 "%s: writing dev_state_path", __func__); 1118 } 1119 break; 1120 default: 1121 break; 1122 } 1123 } 1124 1125 info->curr = NULL; 1126 1127 kfree(dir); 1128} 1129 1130static void scsifront_read_backend_params(struct xenbus_device *dev, 1131 struct vscsifrnt_info *info) 1132{ 1133 unsigned int sg_grant, nr_segs; 1134 struct Scsi_Host *host = info->host; 1135 1136 sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0); 1137 nr_segs = min_t(unsigned int, sg_grant, SG_ALL); 1138 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE); 1139 nr_segs = min_t(unsigned int, nr_segs, 1140 VSCSIIF_SG_TABLESIZE * PAGE_SIZE / 1141 sizeof(struct scsiif_request_segment)); 1142 1143 if (!info->pause && sg_grant) 1144 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs); 1145 else if (info->pause && nr_segs < host->sg_tablesize) 1146 dev_warn(&dev->dev, 1147 "SG entries decreased from %d to %u - device may not work properly anymore\n", 1148 host->sg_tablesize, nr_segs); 1149 1150 host->sg_tablesize = nr_segs; 1151 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512; 1152} 1153 1154static void scsifront_backend_changed(struct xenbus_device *dev, 1155 enum xenbus_state backend_state) 1156{ 1157 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); 1158 1159 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state); 1160 1161 switch (backend_state) { 1162 case XenbusStateUnknown: 1163 case XenbusStateInitialising: 1164 case XenbusStateInitWait: 1165 case XenbusStateInitialised: 1166 break; 1167 1168 case XenbusStateConnected: 1169 scsifront_read_backend_params(dev, info); 1170 1171 if (info->pause) { 1172 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN); 1173 xenbus_switch_state(dev, XenbusStateConnected); 1174 info->pause = 0; 1175 return; 1176 } 1177 1178 if (xenbus_read_driver_state(dev->nodename) == 1179 XenbusStateInitialised) 1180 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); 1181 1182 if (dev->state != XenbusStateConnected) 1183 xenbus_switch_state(dev, XenbusStateConnected); 1184 break; 1185 1186 case XenbusStateClosed: 1187 if (dev->state == XenbusStateClosed) 1188 break; 1189 fallthrough; /* Missed the backend's Closing state */ 1190 case XenbusStateClosing: 1191 scsifront_disconnect(info); 1192 break; 1193 1194 case XenbusStateReconfiguring: 1195 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN); 1196 xenbus_switch_state(dev, XenbusStateReconfiguring); 1197 break; 1198 1199 case XenbusStateReconfigured: 1200 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); 1201 xenbus_switch_state(dev, XenbusStateConnected); 1202 break; 1203 } 1204} 1205 1206static const struct xenbus_device_id scsifront_ids[] = { 1207 { "vscsi" }, 1208 { "" } 1209}; 1210 1211static struct xenbus_driver scsifront_driver = { 1212 .ids = scsifront_ids, 1213 .probe = scsifront_probe, 1214 .remove = scsifront_remove, 1215 .resume = scsifront_resume, 1216 .suspend = scsifront_suspend, 1217 .otherend_changed = scsifront_backend_changed, 1218}; 1219 1220static int __init scsifront_init(void) 1221{ 1222 if (!xen_domain()) 1223 return -ENODEV; 1224 1225 return xenbus_register_frontend(&scsifront_driver); 1226} 1227module_init(scsifront_init); 1228 1229static void __exit scsifront_exit(void) 1230{ 1231 xenbus_unregister_driver(&scsifront_driver); 1232} 1233module_exit(scsifront_exit); 1234 1235MODULE_DESCRIPTION("Xen SCSI frontend driver"); 1236MODULE_LICENSE("GPL"); 1237MODULE_ALIAS("xen:vscsi"); 1238MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
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